ADJUSTABLE BICYCLE HANDLEBAR STEM WITH A BUILT-IN SHOCK ABSORBER

Abstract: An adjustable bicycle handlebar stem comprises a handlebar clamp (1), a post (7) to be clamped in a frame tube and an upper and a lower profile arm (2, 6) between the post (7) and the handlebar clamp (1), with four bearings (A, B, C, D). An adjustment means (8, 11, 13, 16, 17) is built-in substantially between the upper and lower profile arms (2, 6), and it comprises a locking means (8, 13, 16) for arresting the handlebar stem in different angular positions, as well as a cushioning means (8, 11, 17) for shock absorbing in at least some of the arrested angular positions. The adjustment means is remote operated by a lever mounted on the bicycle handlebars.

Description: ADJUSTABLE BICYCLE HANDLEBAR STEM WITH A BUILT-IN SHOCK ABSORBER The present invention relates to a handlebar stem for a bicycle or similar vehicle, i.e. the connecting member which provides fastening to the bicycle frame and which clamps the handlebars themselves. Particularly the invention concerns a handlebar stem which is adjustable, and even more particularly an adjustable handlebar stem with a built-in option for cushioning or shock absorbing. Modern bicycles, particularly bicycles of the "mountain bike" type, "offroad bike", "terrain bike", are often equipped with cushioning or shock absorbing details. For example cushioning front forks of the telescopic type can be found in the market, and springy rear forks and seat stems are also used. The present invention concerns shock absorbers especially for the hands, arms and back of a bicyclist by equipping the bicycle handlebar stem with a cushioning system. The invention is defined precisely in the appended patent claims. For a more detailed illumination of the invention, refe¬ rence will now be made to embodiment examples thereof, and in this connection it is also referred to the appended drawings, where fig. 1 shows an example of a handlebar stem in accordance with the invention, in a side view, fig. 2 shows the same embodiment in a cut-away view in order to make details inside the stem visible, fig. 3 shows single parts of an embodiment of the handle- bar stem in accordance with the invention, and fig. 4 shows an example of an embodiment where the cushioning function can be eliminated. An important feature of the handlebar stem shown in fig. 1 is that its angular position is adjustable by means of a (not shown) lever provided on the bicycle handlebars (not shown) . The handlebars are clamped in the forward handlebar clamp 1, and can be displaced by moving members 1, 2, and 6 about bearings B and D on the top part 3 of the stem post 7, which is fixed in a conventional manner down in the (not shown) forward tube of the bicycle frame. Members 2 and 6 are designated as respectively upper and lower profile arms. It should be noted that the lower profile arm 6 has a longitu¬ dinal opening in its underside, which opening is not shown in the drawing. It is possible to use a parallelogram-type bearing confi¬ guration as well as a non-parallelogram-type configuration for members 1, 2, 3 and 6. Using a parallelogram handlebar guidance, i.e. with distance AC equal to distance BD and also AC parallel to BD, it is achieved that the angular position of the handlebars themselves will remain unchanged when the handlebar stem angle is changed, while the angular position of the handlebars will be rotated somewhat when the stem is lowered/ hoisted in a non-parallelogram embodiment. It is not important for the present invention which type is selected. The lever on the handlebars influences the handlebar stem via cable 19, which cable ends in a pipe socket 5 adapted for locking the handlebar stem angular position in one particular of a number of fixed positions, that is, positions that are fixed while disregarding the cushioning/shock absorbing func¬ tion. The operation of the locking pipe socket 5 as well as the operation of the toothed nut 12 which protrudes somewhat, appear more clearly in fig. 2, to which reference now will be made. In fig. 2, inner parts of the present handlebar stem embodiment appear more clearly. An adjustment means which mainly extends between bearings A and D, comprises details which provide both locking and cushioning operation: An inner pipe 8 (which actually can be rather massively constructed, i.e. the pipe might as well be replaced by a substantially massive cylinder) is fastened to the upper forward axis A by means of a mounting hole 22, and in a rearward direction it is positioned telescopically inside an outer pipe 11 which has its rear end fastened to the lower rearward bearing D. Outside the forward end of the outer pipe 11, there is a specially designed sleeve 9, which is constructed integrally with the above mentioned locking pipe socket 5. This part is designated as an integrated T member 25 (see fig. 3) , and thus it consists essentially of two relatively short pipes 5 and 9 welded together in a T-shape. Sleeve 9 can slide along the outer pipe 11 so far as to engage a forward flange 24 on outer pipe 11 (see fig. 3) . Sleeve 9 is pushed forward toward flange 24 by a powerful spring means, which in the shown embodiment is a coil spring 17 placed around the outer pipe 11 and in its rear end engages the above mentioned toothed nut 12, which nut can be screwed back and forth on a threaded section of the outer pipe 11 in order to adjust the spring force (prestressing) . A tool which engages the nut toothing may be used in this connection. On the underside of inner pipe 8 there is provided a series of conically shaped holes 16. Inside the locking pipe socket 5 there is a piston 13 with a conically shaped stud 23 which is adapted to enter the holes 16. By means of a pre- stressing spring 15 the conical stud 23 of piston 13 is normally held with tension upward inside one of the holes 16, and the angular position of the handlebar stem in relation to e.g. post 7 (actually the angular position of one of the profile arms, e.g. the upper profile arm, in relation to post 7) is then held in a locked position: The inner pipe 8 is then fixed to piston 13 , which further provides a secure connection to the T member 25, which is held fixedly outside the outer pipe 11 between flange 24 and the strong spring 17. It must be noted that also the outer pipe 11 has an opening 21 on the underside thereof (see fig. 3) , i.e. an elongate and longitudinal opening aligned with the holes 16 in the inner pipe 8, in such a manner that the conical stud 23 on the piston passes through this opening to enter a hole 16. If now a large force (from a shock) pushes in a downward direction at the front edge, i.e. on the handlebars, a force is transmitted via the inner pipe 8, piston 13 and T member 25 to the strong spring 17 which is compressed by the T member sleeve 9 which will travel somewhat down the outer pipe 11 together with the inner pipe 8 which slides telescopically. Simultaneously, the profile arms 2, 6 and the handlebar clamp 1 will swing down. The travel possibility is provided by the slit or opening on the underside of outer pipe 11. The power¬ ful spring 17 thereafter provides a return spring action back to the locked angular position. In order to change from one locked angular position to another, the above mentioned lever on the handlebars is opera- ted so that the wire in cable 19 pulls piston 13 with its conically shaped stud 23 back, i.e. downward and out of hole 16. Then the inner pipe 8 is "free" to slide telescopically in the outer pipe 11, i.e. without meeting any resistance from the powerful spring 17. By lifting or lowering the handlebars manually, the inner pipe 8 can be displaced until another hole 16 corresponds with the conical stud 23, which thereafter can be let loose by lever operation to move upward, locking the stem in a new angular position. In order that the movement from one locking position to another shall be perceived good and proper by the bicyclist, i.e. not completely slack, a tensioning spring 26 is provided in order to force two of the movable main members apart, in the present embodiment the tensioning spring is shown posi¬ tioned in the lower forward bearing C. This tensioning spring forces the lower profile arm 6 and the handlebar clamp 1 apart, and provides a faint resistance against downward move¬ ment of the handlebar stem as well as assistance to an upward movement. In the embodiment shown in figs 2 and 3 there is also included an option for adjusting damping in the shock cushion¬ ing action: Inside sleeve 9 there is a slide gasket 20, see fig. 3, having an inside friction layer, i.e. the slide gasket is positioned between sleeve 9 and outer pipe 11. The sleeve 9 is split on top in its entire length (see fig. 3) , and on each side of the split there are tightening details, i.e. a screw thread 10 and a shoulder member 4 for a screw 27, pre¬ ferably an umbraco screw. Tightening the screw 27 will increase the friction against the outer pipe 11 in the cushio¬ ning action, i.e. damping is increased. By tightening the screw completely, the cushioning operation can be eliminated totally. The screw 27 is operated by means of a tool through a hole 28 (fig. 1) in the upper profile arm 2. This must be done in a certain angular position for the handlebar stem, where hole 28 and screw 27 are aligned with each other. As a starting point, the holes 16 are placed in such positions on the inner pipe 8 that a shock cushioning action is achieved for all locked angular positions. However, in certain embodiments it may be favorable to arrange the extreme angular positions (i.e. maximum deflection) , or one of these extreme positions, without any resilient or cushioning action, i.e. completely stiff regarding shocks. Concerning the lower extreme position, it is possible quite simply to place the last hole 16 in a position corresponding to this angular position, and the geometry of the parts themselves will prevent further cushioning action downward. However, regarding prevention of downward cushioning from the upper extreme angular position, a special blocking means must be inserted. Moreover, it is possible to disconnect the cushioning and damping function also in such a manner as shown in fig. 4. A lever or switch on the handlebars is then used, having a cable/wire connection to a pivot arm 30 mounted on sleeve 9. The pivot arm 30 has a conically shaped pin 31 which engages a hole in the outer pipe 11, and hence the damping function is disconnected. The pivot arm 30 can also be operated from the underside of the handlebar stem, i.e. in an embodiment without cable/wire connection. In fig. 4 appears also the per se conventional fixing method for the post 7 to the frame tube, by means of a bolt and a wedge member. The bolt is places in a somewhat deeper recess than in the normal case, from practical considerations. In fig. 3 is shown, as previously mentioned, most of the members taking part in the preferred embodiment, in a state of separation. Member 14 is a screw lid on the underside of the locking pipe socket 5. Screw lid 14 constitutes an abutment for spring 15, and it also operates as a shoulder for the cable sheath 19 from the operating lever on the handlebars. The cable wire ends in a ball resting inside the conical piston stud 23. Member 18 is an eyebolt for providing fastening for the outer pipe 11 to the lower rear bearing D, with a hole 32 adapted to the bearing and a threaded fastening for the outer pipe. The eyebolt may be provided with a flange as an abut¬ ment for spring 17. When the operating lever on the handlebar is released when piston 13 is near a position toward a hole 16, spring 15 will beat the conical piston stud 23 into the hole with an easily perceptible sound when the corresponding position is reached. Such an acoustic signal is useful as a confirmation of locking. In general the present invention utilizes the phenomenon that the distance between two diagonally placed bearings, for instance the upper forward (A) and the lower rear (D) bearings, change when a rotation about the bearings is under¬ taken. The difference between minimum and maximum diagonal distance will in the practical case be in the range 20-50 mm. As for spring forces, the powerful spring will in a state of complete compression provide a force of about 150-250 kp, while the tensioning spring 26 and the piston spring 15 are dimensioned with a much weaker force. Other spring types than the helical springs 15 and 17 shown here, can possibly be used, for example resilient pads or similar. Further, it will be possible to place the adjustment means between the two other bearings, that is bearings B and C, however then with reversal of certain functions. Quite generally it is also possible to provide a stepless adjustment of the locked angular positions, for instance with a clamp means instead of the conical stud and holes, but a solution of the type described above in detail, is preferred due to the simple construction thereof. However, the various possible variants within the scope of the invention, are those comprised by the appended patent claims, and particularly by patent claim 1.

Claims: P A T E N T C L A I M S 1. A handlebar stem for a bicycle or a similar vehicle, comprising a post (7) to be clamped in a frame tube, forward extending upper (2) and lower (6) profile arms journalled to a top part (3) of said post (7) as well as a forward handlebar clamp (1) journalled to both upper and lower profile arm (2, 6), c h a r a c t e r i z e d b y an adjustment means (8, 11, 13, 16, 17) operated by a handlebar lever via mechanical or hydraulical transmission (19) and built-in substantially between upper (2) and lower (6) profile arm, said adjustment means comprising a locking means (8, 13, 16) for arresting the handlebar stem in different angular positions in relation to said post, as well as a cushioning means (8, 11, 17) for providing shock absorbing in at least some of the arrested handlebar stem angular positions. 2. Handlebar stem in accordance with claim 1, c h a r a c t e r i z e d i n that said cushioning means is constituted by an inner pipe (8) which is able to slide tele¬ scopically in an outer pipe (11) while under pre-tension by a spring (17) . 3. Handlebar stem in accordance with claim 2, where the upper and lower profile arms (2, 6) are journalled to said post (7) in respectively upper rear bearing (B) and lower rear bearing (D) , as well as to the handlebar clamp (1) in respec¬ tively upper forward bearing (A) and lower forward bearing (C), c h a r a c t e r i z e d i n that said inner pipe (8) is fastened to said upper forward bearing (A) and said outer pipe (11) is fastened to said lower rear bearing (D) . 4. Handlebar stem in accordance with claim 3, c h a r a c t e r i z e d i n that said spring (17) is a powerful helical spring around and outside said outer pipe (11) , with rear engagement against a flange on an eyebolt which is fastened to said lower rear bearing (D) , optionally against a toothed nut (12) which can be displaced on outside threads on the outer pipe (11) for adjustment of the pre- tension of said spring (17) , and having a forward engagement against the rear end of a substantially cylindrical sleeve (9) positioned slideably and concentrically outside the forward end of the outer pipe (11) , the forward edge of said outer pipe (11) having a flange (24) for restricting the forward sliding movement of said sleeve (9) . 5. Handlebar stem in accordance with claim 4, where said locking means (8, 13, 16) is adapted for locking the handlebar stem in a fixed number of arrested angular positions, e.g. five such angular positions, c h a r a c t e r i z e d i n that said locking means comprises a wire operated and spring pre-tensioned piston (13) able to move inside a locking pipe socket (5) which is con¬ structed integrally with said sleeve (9) and placed substan- tially perpendicularly downward therefrom, said pipe socket (5) extending down through a longitudinal opening in said lower profile arm (6) , so that a conically shaped stud (23) on said piston (13) may enter into one of a number, e.g. five, conically shaped holes (16) placed along the underside of the inner pipe (8) , through an opening on the underside of said sleeve (9) , which opening is aligned with the axial opening of said locking pipe socket (5) , and through an elongate and longitudinal opening (21) in the outer pipe (11) . 6. Handlebar stem in accordance with claim 5, c h a r a c t e r i z e d i n that said sleeve (9) has a longitudinal split on top and on each side thereof respec¬ tively a screw thread (10) and a shoulder (4) welded to the sleeve for screw tightening of the sleeve (9) around a slide gasket (20) having an inside friction layer, for adjustment of the sliding friction against the outer pipe (11) and hence adjustment of the damping of the cushioning movement, said upper profile arm (2) being equipped with an adjustment hole (28) for insertion of a tool to rotate a damping adjustment screw (27) in a predetermined angular position for the handle¬ bar stem. 7. Handlebar stem in accordance with one of claims 3-6, c h a r a c t e r i z e d i n that a return spring (26) is placed in connection with one of the bearings (C) to provide resistance against adjustment of the handlebar stem to a lower position and an assisting force when adjusting to a higher position. 8. Handlebar stem in accordance with one of claims 5-7, c h a r a c t e r i z e d i n that said locking pipe socket (5) is closed in its lower end by a screw lid (14) which constitutes an abutment for a cable sheath and which has a passage for a wire (19) fastened inside to said conical piston stud (23) . 9. Handlebar stem in accordance with one of claims 5-8, c h a r a c t e r i z e d i n that the forwardmost of the conical holes (16) on the underside of the inner pipe is placed in a position which is adapted to a full downward angular deflection for the handlebar stem, whereby shock absorbing/cushioning is prevented in this position. 10. Handlebar stem in accordance with one of claims 5-9, c h a r a c t e r i z e d b y a locking device for preven¬ ting shock absorbing/cushioning when the handlebar stem has a full upward angular deflection.

Inventors: HALS CATO, HALS, CATO
Applicants: HALS BIOMECHANICS AS, HALS, CATO
Application year: 1994
Main classification: B62K21
IPC codes: B62K21